Shaky Faultline Raises
Threat Of Super-Volcano
By Leigh Dayton
Science Writer
The Australian

As if earthquake-ravaged Indonesia doesn't have enough to worry about, now scientists warn that a Sumatran super-volcano might blow its top at any time.
If it does, the blast will toss hundreds of thousands of cubic kilometres of rock and ash into the atmosphere, dwarfing the eruptions of Krakatoa, Mount St Helens, Pinatubo and any conventional volcanic explosion of the past tens of thousands of years.
"These super-volcanoes are potentially the greatest hazard on Earth, the only greater threat being an asteroid impact from space," said Ray Cas, a vulcanologist with Monash University in Melbourne.
Professor Cas said a "major tectonic event" could be enough to trigger a deadly super-volcanic eruption.
The likelihood that the Toba ñ the largest super-volcano on Earth ñ will erupt has increased significantly due to geological stresses generated by the recent quakes.
Worse, Toba sits directly atop the faultline running down the spine of Sumatra. That is where seismologists say a third quake might strike.
Because of the increased risk, Professor Cas called for increased monitoring of Toba.
"With enough precursor information and signals like gas releases, we (could) warn of a significant eruption in days, weeks or months," he said.
Professor Cas's call follows a report early this month to the British Government's Natural Hazard Working Group by the Geological Society of London. The report called for increased awareness of the risks posed by super-volcanoes and development of mitigation strategies.
Vulcanologist Stephen Self of Britain's Open University said a super-volcanic eruption might cover an entire continent with ash that could take decades to erode.
"(Such an eruption) could result in the devastation of world agriculture, severe disruption of food supplies and mass starvation," he told the online journal LiveScience.
Professor Cas said super-volcanoes tended to erupt in 2000-year cycles. The Toba super-volcano last erupted 73,000 years ago.
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